US2755794A - Sealed heater venting system - Google Patents

Description

S. I. WENDELL.

SEALED HEATER VENTING SYSTEM Filed March 27. 1952 Ww/@ @f5 ggf; @wg mfc United States Patent() SEALED HEATER VENTIN G SYSTEM Samuel I. Wendell, Indianapolis, Ind., assignor to Stewart- Warner Corporation, Chicago, lll., a corporation of Virginia Application March 27, 1952, Serial No. 278,794

7 Claims. (Cl. 126-307) The present invention relates generally to the art of heating systems, and more particularly to gas heating systems ofthe sealed type. A sealed gas heater of this general character is shown in the patent to Allen W. Lundstrum, No. 2,160,883.

Heating systems of the sealed type have the distinguishing characteristic that ali of the air for combustion is taken in from outside the building and the exhaust gases also pass to a point outside the building, the system being sealed so that it is impossible for the air within the building to become contaminated or otherwise interconnected with the combustion side of the heater. Sealed systems have the further advantage that since they do not use air from within the building either for combustion or for dilution of the exhaust gases, it is not necessary that cold outside air be admitted to the building to take the place of exhaust air. Heating systems of this type are thus distinguished from those more commonly used in which air for combustion is simply taken from the room in which the heater is located and the exhaust from the heater is returned directly to the atmosphere within the space to be heated. Normally the connections are such that the rising exhaust gas is trapped within a downwardly facing open ended pipe or the equivalent and carried through a ue to a point outside the building along with a considerable quantity of the air within the room. Heaters of this latter type are not particularly sensitive to wind and other atmospheric conditions at the flue outlet in spite of the fact that changes in wind velocity will have the effect of markedly changing the flow rate through the exhaust ue and will frequently cause downdrafts since these changes do not affect the heater, the heater essentially not being connected to the hue.

it will be appreciated, therefore, that heaters of the type forming the subject matter of the present invention, although having distinct advantages, nevertheless have the characteristic of being extremely sensitive to any change in pressure at either the combustion air inlet or exhaust outlet if this change is not exactly duplicated at the other opening. It is a difficult problem, therefore, to provide connections to the atmosphere at both the exhaust and inlet openings in such fashion that changes in the direction and velocity of the wind will not appreciably affect the flow rate through the heater, since the ow rate through the heater is established simply by the convection rate or, in other words, by the temperature of the gases within the heater itself, and the vertical length of the outlet flue. This pressure differential between the inlet and outlet of such a heater system, which produces the ow of combustion air therethrough, is extremely slight and therefore slight pressure changes at the inlet and outlet openings of the heater produced by changes in wind velocity will affect the combustion air ow rate very markedly. Sealed heaters are particularly sensitive to conditions which cause down-drafts which will snu out the pilot even if only of momentary duration. Systems such as that proposed in the before mentioned patent overcome this difficulty by overcompensation, that is, by

causing a positive flow of combustion air in the proper direction under all wind conditions. Such systems suffer from inefficiency when the wind is strong because of excessive. combustion air ow.

In view of the above it isl one of the objects of the present invention to provide a vent' system for sealed gas heating system having connections for both the incoming and outgoing combustion air ata point outside the building to be heated in such fashion that the combustion air convection flow rate through the heater is not disturbed appreciably by changes in windY direction and magnitude at the two combustion air openings.

Another object of the present invention is to provide a novel fitting or vent of good appearance which may be manufactured at low cost and which may be attached to a sealed heater so as to make the combustion air ow rate through the heater substantially insensitive to wind velocity.

Yet another object is to provide an improved venting system and vent tting which so accurately compensates for wind effects as to make substantial overcompensation unnecessary.

Still an additional object is to provide a novel venting system and vent lling of the above type which insures against reverse flow under all wind conditions without causing excessive flow in the pro-per direction even under high wind conditions.

Other objects andl advantages will become apparent from the following description of a preferred embodiment of my invention which is illustrated in the accompanying drawings.

In the drawings, in which similar characters o-f reference refer to similar parts throughout the several views- Fig. l is a front view of a recessed wall heater of the general type to which the fitting or vent of the present invention may be attached to'advantage;

Fig. 2 is a vertical transverse sectional view through the heater of Fig. l and the flue and vent connection forming the principal subject matter of the present invention with the structure of the heater shown diagrammatically;

Fig. 3` is a medial sectional view of the combustion air outlet and inlet vent and may be considered as a portion of Fig. 2 drawn to larger scale; and

Fig. 4 is a front view of the vent of Fig. 3 as seen when mounted upon a building and ready for use.

Referring to Fig. l of the drawings, it will be seen that a typical heater of the type to which the present invention is well adaptedto be used consists of a cabinet lill which covers mechanism recessed within an outside wall. This cabinet has Ventilating hot air outlet louvres 12 near the upper end thereof while inlet louvres 14 and a heater control knob 16 are located near the lower end of the heater casing. Since details of the construction of the heater itself do not formv a portion of the present invention, and since a heater of this general type is described in detail in the before mentioned patent, the general description that follows of the heater itself is primarily for the purpose of orientation.

Referring to Fig. 2 of the drawing, it will be seen that Within the case 1li there is a sheet metal liner 13 generally termed a rou'ghing box, which is recessed withinI the space within a wall where the heater is located. `The heater proper comprises a hollow heat exchanger 20 having a burner 22 located within the lower end thereof, this burner being controlled in any well known manner by the knob 16 and usually by a room thermostat not shown. The heat exchanger 20' is sealed and at a point near the top is connected by a tube 24 to an outlet opening by means of which exhaust gases are conveyed from the heater to a point outside the building. At its lower end the heat exchanger 20 is also connected by means of a spud 26 to a vertically extending sheet metal plenum passes, the inlet pipe being somewhat larger so as to provide an annular space between the two communicating with the plenum chamber 28. To facilitate assembly, the duct 24 may be constructed so that the inner portion telescopes inside of a somewhat larger sleeve or duct 32 which leads to the outside.

Within the heater casing l a shroud or detlector 34 is positioned somewhat behind the heat exchanger 2t) and at its upper end is curved outwardly so that air to be heated enters through the louvres 14, passes upwardly around the heat exchanger by convection, and outwardly at the upper louvres l2, the deflector 34 aiding in the direction of the air.

It is thus seen that when the heater is in operation the Ventilating air is circulated by convection and that the air for combustion is likewise brought in at the lower end of the heat exchanger and passes outwardly at an upper point with respect to the inlet and also circulates by convection. Further, the outlet duct 32 for the combustion side of the heater passes through the outer wall of the building to the outside while the inlet air is conveyed inwardly from outside the building through the sleeve which is concentric with the outlet fitting 24.

The vent structure indicated generally by the numeral 36 is made up of several sheet metal elements and is secured to the outer end of the outlet sleeve 32 and covers, although it does not seal, the outer end of the somewhat larger duct 36. The members which comprise the vent are secured to a flat sheet metal mounting plate 38 which is generally rectangular with rounded corners and which is secured to the outer face of the building, with a hole in the center of the plate loosely surrounding the end of the inlet duct 30. It is sealed thereto in substantially airtight relation by a packing gland 40 which consists of a channel shaped ring welded to the inner face of the plate 38 with the ring confining a suitable heat resisting resilient substance which engages the external surface of the duct 30. The plate 38 at the time of installation is calked around its edges so as to prevent rain water from getting between the metal plate and the surface of the building 1 to which it is attached.

The vent fitting is shown more particularly in Fig. 3 and comprises a hat-shaped ow division member 42 of pressed metal which is extruded to provide a short tubular spud 44 at its center which slips inside and closely fits the outer end of the outlet duct 32. From the outer end of the duct portion 44 the outwardly dished metal crown surface 46 slopes radially outwardly and inwardly toward the building at a comparatively shallow angle, about 20, to a plane transverse to the duct axis to a position outwardly of the center line such that this position is radially outwardly of the inlet duct 30 by a distance approximately equal to the distance between the ducts 32 and 3i). From this position the metal extends straight inwardly so that the surface at this point forms a cylindrical deflector or skirt 48 coaxial with the cylindrical duct 32.

At the inner end of the cylindrical portion 48 the metal is flared straight outwardly for a short distance forming a radial annulus merging with a peripheral edge that is rolled tor turned backwardly to an angle of approximately with respect to the face of the plate 38. The at portion, indicated by the numeral 50, is parallel to the surface of the plate 38 and is supported therefrom by short sheet metal brackets 52 spot welded both to the face of the plate 38 and to the inner surface of the member 42. Three or four of these clips are sufficient to insure rigidity and it has been found that they have little if any influence upon the air ow around and into the inlet duct 30. The length of the supporting members 52 is such that the innermost portion of the fitting 42, that is the surface 50, is spaced approximately one inch from the outer face of the mounting plate 38.

The exhaust passes outwardly through the central opening 44 which is covered by a cap S4 supported from the outer face of the inwardly inclined annular surface 46 by means of sheet metal brackets S6 spot welded to the members 46 and 54 so that these two members constitute a rigid assembly. The cap member 54 is formed so as to be generally a spherical segment and has a diameter approximately equal to the diameter of the fitting 42 at the outer periphery of the sloping surface 46. The curvature of the cap member 54 is such that its surface is approximately parallel to the sloping face 46 where it lies outwardly of the sloping face and is smoothly curved so as to be tangent to a plane at right angles to the center line of the center of the cap. The cap 54 is spaced outwardly at its edge from the edge of the sloping face 46 by an amount slightly greater than the distance between the ilat surface 5t) and the face of the mounting plate 38.

With the device in use, the exhaust of the heater passes outwardly to the atmosphere through the peripheral slot formed between the cap member 54 and the hat shaped inner member 42. Air for combustion is taken inwardly between the inner rim 50 of the hat-shaped member 42 and the flat mounting plate 38. Inasmuch as the device is circular and therefore symmetrical about the horizontal longitudinal axis, it is apparent that the device is unaffected by changes in the angularity of the Wind around this axis. Also since the openings are relatively close together and have much the same entrance and exhaust conditions for the wind excepting for the narrow outwardly rolled edge of the member 42, any change in the wind component which can be measured in a plane which includes the axis of the device does not appear to create a condition at one of the openings which diifers over that at the other excepting that a slightly higher pressure is created at the inlet by the rolled edge. The pressures at both the inlet and outlet remain, therefore, almost constant with respect to each other, although they may vary somewhat with respect to atmospheric pressure generally. The amount of overcompensation is therefore extremely slight, but is nevertheless suticient to prevent the possibility of backdrafts. The spacing provided between the inlet opening and the outlet opening, that is, the length of the cylindrical portion 42 is sufficient to prevent appreciable mixing of the outgoing exhaust with the incoming air for combustion.

Although in the last paragraph some attempt has been ymade to speculate upon the reasons for the satisfactory functioning of the device, the fact remains that changes in conditions which are less than is readily measurable, particularly reverse ilow, will upset a gas flame and therefore the actual appearance of the ame itself is the only real criterion of proper operation. Results indicate that with a vent of the type disclosed, a flame has a substantially unchanged appearance even though the wind at the vent may be anything up to whole gale `force in any direction and overcompensation is Safely reduced to the point where the carbon-dioxide content of the exhaust gases does not fall below about live and one-half per cent even with winds of sixty miles per hour. This compares extremely favorably with still air operation under which conditions a carbon dioxide content of about eight per cent can be achieved. This slight overcompensation has been found to be enough to insure against backdrafts even under gusty conditions` Having described my invention, what I claim as new and useful and desire to secure by Letters Patent of the VUnited States is:

.outer central portion and an inwardly extending generally cylindrical skirt on the peripheryof the central portion,

said member' having an opening therethrough on the axis thereof to'be connected to the smaller of said inlet and outlet openings and adapted to cover the larger of said openings, said member being adapted to define with the wall surface of the building a peripheral slot therearound of substantially uniform width communicating with the larger of said openings, and a convex substantially spherical segmental cover for the smaller of said air openings having substantially the same diameter as said central portion of said hat shaped member and secured to said member in spaced relation thereto to provide a peripheral slot of substantially uniform width between said cover and said hat shaped member communicating with the smaller of said air openings, the convex central portion of said hat shaped member having generally the same shape as the opposing annular portion of said cover and having a generally uniform spacing therefrom.

2. A vent for a sealed heater having concentric inlet and outlet combustion connections, said vent adapted to be positioned upon the outer surface of a building to be heated by said heater, said vent comprising; a hat shaped member formed as a surface of revolution with a convex outer central portion adapted to cover the larger of said connections and connected to a coaxial annular rim by a short cylindrical portion, said member having an opening therethrough on the axis thereof adapted to be connected to the smaller of said inlet and outlet connections, said member being adapted to coact with the surface of the building to provide a peripheral slot therearound of substantially uniform width communicating with the larger of said connections, and a convex substantially spherical segmental cover for the smaller of said air connections having substantially the same diameter as said central portion of said hat shaped member and secured to said member over said central opening thereof and in spaced relation thereto to provide a peripheral slot of substantially uniform width between said cover and said hat shaped member communicating with the smaller of said air connections, the convex central portion of said hat shaped member having generally the same shape as the opposing annular portion of said cover.

3. A wind compensated outside vent fitting for connection to concentric inlet and outlet duct ends, said vent fitting being adapted for attachment to the outer surface of a building, said vent fitting comprising; a hat shaped member formed as a surface of revolution with a convex outer central portion adapted to cover the larger of said duct ends, a deector skirt portion extending inwardly from the periphery of said central portion of the member, and an annulus extending generally radially outward from the inner end of said skirt portion; said member having an opening therethrough on the axis thereof to be connected to the smaller of said inlet and outlet duct ends, said member being adapted to coact with the surface of the building to provide a peripheral slot therearound of substantially uniform width communicating with the larger of said duct ends, and a convex cover for the smaller of said duct ends secured to said hat shaped member over said opening therethrough in spaced relation thereto to provide a peripheral slot of substantially uniform width between said cover and said hat shaped member communicating with the smaller of said duct ends, and said central portion of said hat shaped member having a substantially uniform spacing from the opposing annular portion of said cover.

4. A combined inlet and outlet vent adapted to be mounted on the vertical exterior wall of a building and comprising, in combination, a first duct adapted to extend horizontally through the building wall, a second duct of smaller size concentric with said first duct and extending outwardly somewhat beyond the effective outer end of said first duct, a flow division member on the outer end of said second duct having a circular outwardly dished crown portion disposed beyond the outer end of said first duct and extending radially therebeyond, an outwardly convex circularcap disposed outwardly of said crown in circumferentially uniform spaced relation thereto toform therewith an annular opening communicating with said second duet, said cap having a diameter substantially equal to that of said crown, a cylindrical deflector integral with the peripheral edge of said crown and extending away from saidcap, a radial annulus integral with the edge of said cylindrical deflector remote from said crown and extending radially outward, the outer marginal edge of said annulus being turned backwardly in the general direction of said annular opening, and said annulus and said turned edge being adapted to define with the outer surface of the wall to which said vent i-s attached an annular opening communicating with said first duct.

5. A combined inlet and outlet Vent comprising, in combination, plate means adapted to be mounted lon the exterior vertical wall of a building, means defining an air inlet in said p'late means, horizontal exhaust duct means concentric with said Iair inlet means and extending outwardly beyond the effective outer end of said air inlet means, a ow division member `on `t-he outer end of said exhaus't duct and including an annular crown member extending radially outward in relation to said exhaust duct, a cylindrical deflector extending from said crown member toward said plate means, an annulus extending radially outward from the edge of said deflcctor adjacent said plate means, said `annulus fbeing disposed radially outward of said inlet means and defining with said plate means an annular air inlet, and a generally vertical circular cap mounted in horizontally spaced relation `to said crown and defining therewith a circumferentially uniform annular outlet yfrom said exhaust duct means.

6. A combined inlet and exhaust vent device adapted to be mounted on an exterior vertical -building Wall and comprising, in combination, first duct means adapted to extend horizontally through `the building wall, second duct means 4of smaller size concentric with said first duct means and extending outwardly beyond the effective outer end `of said lirst duct means, a flow division member on the outer end of said second duct means and including an annular crown portion extending radially outward in relation to said first duct means in outwardly spaced relation to the effective outer end thereof, said crown portion being larger in diameter than said first duct means, a cylindrical deflector larger in diameter than said first duct means and extending from said division member crown toward said first duct lto define with the vertical surface of the building wall with which the vent is used lan annular opening communicating with said first duct means, and a cap conforming generally in shape to said crown and mounted in circumferentially uniform spaced relation to tthe latter to define therewith an annular opening communicating with said second duct.

7. A combined inlet and outlet vent adapted to be mounted on a vertical building wall and comprising, in combination, a first duct adapted to extend horizontally through -the building wall, a second duct of smaller size concentric with said first duct and extending outwardly beyond the effective outer end thereof, la flow division member including a centrally open crown portion a't the outer end of said second duct and extending radially therefrom, said crown being circular in shape and having a diameter larger than that of said first duct, a cylindrical deflection member integral with the outer periphery of said crown portion and substantially coaxial wi'th said first and second ducts, an annulus extending radially outward from the peripheral edge of said deflection niember and adapted to define with the adjacent surface of the building wall an annular opening communicating with said first duct, Ia circular cap having a diameter 'approxin ma'ting that of said crown, `and said cap 4being disposed outwardly of said crown land outwardly `of the outer pe ripheral edge of said deflection member in uniformly spaced relation thereto to dene therewith an annular 186,054 opening communcang with said second duct. 217,712 424,778

References Cited in the file of this patent 757,348

UNITED STATES PATEN IS 2,160,883

183,520 Vaile Oct. 24, 1876 8 Mihan Ian. 9, 1877 Smith July 22, 1879 Gee Apr. 1, 1890 ,Ross Apr, 12, 1904 Martin July 27, 1937 Lundstrum June 6, 1939

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